微观经济学 Chapter-10-助教张翔

Chapter10

OligopolyandMonopolisticCompetition

黄新飞

InternationalBusinessSchoolSun－YatSenUniversity2MarketPowerMarketpowersignifiesthedegreeofcontrolthatafirmorasmallnumberoffirmshasoverthepriceandproductiondecisionsinanindustry.Themostcommonmeasureofmarketpoweristhefour-firmconcentrationratio.3FirmOutputFirm1 25Firm2 20Firm3 15Firm4 10Firm5 8Firm6 7Firm7 5Firm8 5Firm9 3Firm10 2=70Four-FirmConcentrationRatioConcentrationRatios:

c4=

q1+q2+q3+q425+20+15+10100Q==70%4CigarettesHouseholdrefrigeratorsElectriclightbulbsMotorvehiclesGreetingcardsBlastfurnacesScrewproducts5%_4%Tools,dies,andjigs3%_2%93%82%86%84%84%37%7%16%8%7%4%21%4largestcompaniesNext4largestcompanies5WarningonConcentrationConventionalconcentrationmeasuresincludeonlydomesticproductionandexcludeimports.Conventionalconcentrationmeasuresalsoignorethegrowingimpactofcompetitionfromotherindustries.6TheNatureofImperfectCompetitionEconomistshavefoundthatthreemajorfactorsarepresentinimperfectlycompetitivemarkets:CostsBarrierstocompetitionStrategicinteraction

(策略互动)7 Percentageofindustry outputproducedbythe

Industry fourlargestfirms.ChewingGum 96% Householdlaundryequipment 93Cigarettes 92Electriclamps(bulbs) 91Motorvehicles 90Smallarmsammunition 88Primarycopper 87Breakfastcereals 87Beerandmaltbeverages 87Householdrefrigerators 85Greetingcardpublishing 85Bookpublishing 24% Upholsteredfurniture 24Woodfurniture 20Metalhousefurniture 18Paperboardboxes 16Bolts,nuts,andrivets 16Furgoods 16Women’sandmisses’suitsandcoats 13Metaldoors 13Women’sandmisses’dresses 6OligopolyMonopolisticCompetition8StrategicInteractionDescribeshoweachfirm’sbusinessstrategydependsontheirrivals’strategies.Asthenumberoffirmsinanindustryshrinksandindustryconcentrationgrows,eachfirmismorelikelytobasepricingandoutputdecisionsonhowotherfirmsintheindustryarelikelytorespond.9TheoriesofImperfectCompetitionThreeofthemostimportantcasesofimperfectcompetition:Collusiveoligopoly(合谋寡头)MonopolisticcompetitionSmall-numberoligopoly10CooperativeandNoncooperativeBehaviorWhenthereareonlyasmallnumberoffirmsinamarket,theyhaveachoicebetweencooperative

(合作)andnoncooperative

(非合作)behavior.中国案例分析：华为侵权案7月28日，华为公司、思科公司、3COM公司向得克萨斯州东区法院马歇尔分院提交了终止诉讼的申请，法院遂签发法令，终止了思科对华为的诉讼。一个是全球最大的网络设备制造商，一个是中国年轻的网络设备制造商。思科占据着全球垄断性地位，市值1000多亿美元，年收入近200亿美元。在这场全球化的残酷对决中，华为孤军作战且创造了“神话”，和解其实就已经是胜利。12CollusionCollusionoccurswhenoneormorefirmsjointly(共同地)setpricesoroutputs,dividethemarketamongthemselves,ormakeotherbusinessdecisionsjointly.Suchcollusioncanbeeitherexplicitortacit(公开的或默许的).13ExplicitCollusiveOneexampleofexplicit(清楚的，公开的)collusionwouldbethatoftheGildedAgeoligopolists(市场供应垄断者)intheearlyyearsofAmericancapitalism.Theseoligopolistsformedtrustsorcartels(托拉斯或卡特尔)tosetprices.TheAntitrustLaws14In1960,someexecutivesatGeneralElectric,Westinghouse,andAllis-Chalmers,amongothers,cookedupaschemetofixpricesinthemarketforheavyelectricalequipmentsuchastransformers,turbines,andcircuitbreakers.PhasesoftheMoonConspiracy15MorePricingFixingIn1993,Borden,Incorporatedpaid$8millioninfinesforfixingbidsonmilksoldtoschools.Bristol-MeyersSquibbandAmericanHomeProductspaid$5millionin1992tosettlechargesthattheyhadfixedpricesonbabyformulas.16ColaAndFaxPaperInacolawarmeltdown,localexecutivesforbothCocaColaandPepsiCowenttoprisonforconspiringtofixsoft-drinkpricesinVirginia.Mitsubishipledguiltyandpaida$1.8millionfineforconspiringtoraisethepriceoffaxpaper.17PriceLeaderTacitCollusionThebroaderproblemiswithimplicitortacitcollusionthatarisespreciselybecauseexplicitcollusionisillegal.Thewordtacitmeansto“expressorcarryonwithoutwordsorspeech.”

Andtacitcollusionissaidtooccurwhenfirmsinanindustryrefrainfromcompetitionwithoutexplicitagreements.18BarriersFirst,collusionisillegal.Second,firmsmay“cheat”ontheagreementbycuttingtheirpricetoselectedcustomers.Third,manycompaniesfaceintensivecompetitionfromforeignfirmsaswellasdomesticcompanies.19ThreeBasicModelsCartelPriceLeaderKinkedDemandDQPTheKinkedDemandTheory元/数量数量MRD如果厂商降低价格，其他厂商也会跟着降低价格，结果，需求相对缺乏弹性。如果厂商将价格提高到P*之上，其他厂商不会提高价格，则需求变得富有弹性。P*AE美元/数量DP1Q1MCMC’只要MC仍然在MR的垂直区域内，那么，价格与产量仍保持不变。MR数量AEBN折弯的需求曲线22ANegotiatedPriceTheythennegotiatewhatpriceshouldbechargedfortheproduct.And,ofcourse,aspartoftheirsecretcartelagreement,eachfirmwillalsohavetoagreetorestrictitsoutputsothepricecanbemaintainedinthemarket.23AQuestionSowheredoyouthinktheseoligopolistswillsetprice?

a)Theoligopolywillsetpriceequaltomarginalcost.b)Theoligopolywillsetmarginalrevenueequaltomarginalcost.c)Thisisanincrediblyobscurequestion.24TheAnswerSowheredoyouthinktheseoligopolistswillsetprice?

a)Theoligopolywillsetpriceequaltomarginalcost.b)Theoligopolywillsetmarginalrevenueequaltomarginalcost.c)Thisisanincrediblyobscurequestion.Iftheoligopolistscantrulycoordinatetheiractivities,theobviouspricetosetisthesameasthatwhichwouldbesetbyamonopolist.25CheatingValue产量如果其他人保持价格不变搞欺骗的企业的好处价格如果所有企业价格同时变化课堂测试：古诺模型双寡头模型假设市场需求曲线P=30–Q，并且Q=Q1+Q2MC1=MC2=0如何推导厂商1和2的反应曲线27MonopolisticCompetitionMonopolisticcompetitionresemblesperfectcompetitioninthreeways:1.Theremanybuyersandsellers,2.Entryandexitareeasy,3.Firmstakeotherfirms’pricesasgiven.28ProductDifferentiationThedifferencefromperfectcompetitionisproductdifferentiation

(产品差异).Productdifferentiationleadstoadownwardslopeineachseller’sdemandcurve.29MonopolisticCompetitionVSoligopolyTherearethreekeydifferencesbetweenoligopolyandmonopolisticcompetition.1.Amonopolisticallycompetitiveindustryisrelativelyunconcentrated.2.Collusionsareimpossible.3.Thereisnofeelingofmutualinterdependenceamongfirms.30PriceMCACWhatisthepriceandquantityinthisindustryandwhataretheeconomicprofits?a)PriceisP1,quantityisQ1andeconomicprofitsareBHG.PriceissetwhereMCintersectsdd.b)PriceisP2,quantityisQ2,andeconomicprofitsareP1P2GB.PriceissetwhereMRequalsMC.c)IfIhadacomputer,Icouldfigureitout.MonopolisticcompetitionbeforeentryP2P1GdBMRHd31PriceMCACWhatisthepriceandquantityinthisindustryandwhataretheeconomicprofits?a)PriceisP1,quantityisQ1andeconomicprofitsareBHG.PriceissetwhereMCintersectsdd.b)PriceisP2,quantityisQ2,andeconomicprofitsareP1P2GB.PriceissetwhereMRequalsMC.c)IfIhadacomputer,Icouldfigureitout.MonopolisticcompetitionbeforeentryP2P1GdBMRHd32ACd'd'MCdPriceAtwhatpointwillentrycease?a)Entrywillceasewheneachsellerhasbeenforcedintoalong-run,no-profittangencysuchasatG'.b)EntrywillceasewhereMCequalsAC.c)EntrywillceasewhenBillGatessaysitwill.MonopolisticcompetitionafterentryddG’MR33ACd'd'MCdPriceAtwhatpointwillentrycease?a)Entrywillceasewheneachsellerhasbeenforcedintoalong-run,no-profittangencysuchasatG'.b)EntrywillceasewhereMCequalsAC.c)EntrywillceasewhenBillGatessaysitwill.MonopolisticcompetitionafterentryddG’MR34ACd'd'MCdPriceMonopolisticcompetitionafterentryddG’MRP1P=MCEachproducerisontheleft-handdecliningbranchofitslongrunaveragecostcurve.Whatdoyouthinkthismeansformarketperformance.35ACd'd'MCdPriceMonopolisticcompetitionafterentryddG’MRP1P=MCAInthelongrun,monopolisticcompetitionisneitherallocativelyorproductivelyefficient.Anunderallocationofresourcesoccursintheindustrybecausetheproductpriceexceedsmarginalcost.ProductiveefficiencyisnotrealizedbecauseproductionoccursatpointG'wheretheaveragetotalcostexceedstheminimumattainablecostatPointA.36Non-PriceandAggressiveAdvertisingThefactthatthatmonopolisticcompetitionisbothallocativelyandproductivelyinefficientrelativetotheperfectcompetitionresultisnottheonlyproblemwithmarketperformance.AtleastsomeeconomistsarguethatmonopolisticcompetitionleadstobothexcessiveadvertisingandneedlessbrandproliferationReducingthenumberofmonopolisticcompetitors,whilecuttingcosts,mightwellenduploweringconsumerwelfarebecauseitwouldreducethediversity(多样性)ofavailablegoodsandservices.37GameTheoriesCompetitionamongthefewforcesfirmstotakeintoaccountcompetitors’reactionstopriceandoutputdeviations(背离)andbringsstrategic(战略的)considerationsintotheirmarkets.Thisanalysisistheprovinceofgametheory(博弈论).38DivorceofOwnershipandControlIn1996,morethan2.3millionpeopleownedAT&T’sshares.Becausethestockoflargecompaniesissowidelydispersed(被分散的),ownershipistypicallydivorcedfromcontrol.ThreeConflictsofInterest39RationalityandRulesofThumbIntherealworld,peoplehavelimitedresourcesandinformationtomakedecisions,sofirmsorconsumersoftenexhibitboundedrationality(有限理性).Thismeansthattheyusuallystrivetomakeagooddecision,ratherthanwasteresourceshuntingfor(追逐)thebestdecision.40TheEconomicsofInformationBecauseinformationiscostlytoproducebutcheaptoreproduce,marketsininformationaresubjecttoseveremarketfailures(市场失灵).Theinabilityoffirmstocapturethefullmonetaryvalueoftheirinventions(发明)iscalledinappropriability(非专用性).IntellectualPropertyRight41AreMonopoliesBad?ThequestionfirstraisedbyHarvardeconomistJosephSchumpeteriswhethermonopoliesarelikelytooutperformcompetitiveindustriesinthedynamicefficiencydimension.Iftheanswerisyes,thenperhapsweshouldjustleavemonopoliesalone.JosephSchumpeter1883-195042IndustrialR&DPerformanceBySizeofCompanySizeofCompanyR&D-SalesRatio(%)TotalCompanyR&D（$,billions）

1999(employees)19831999Fewerthan5002.28.931.3500to999na4.06.41,000to4,9992.03.123.95,000to9,9910,000to24,9992.32.824.525,000ormore3.42.059.9课堂测试假设（1）只有A、B寡头厂商出售同质且生产成本为零的产品；（2）市场对该产品的需求函数为Q=240-10P；（3）厂商A先进入市场，随着B进入。各厂商确定产量时认为另一厂商会保持产量不变。试求：a.均